Tool holder for machine tools



July 21, 1942.

S. L. STENBERG TOOL HOLDER FOR MACHINE TOOLS Filed Nov. 14, 1939Patented July 21, 1942 STATS Application November 14, 1939, Serial No.304,399 In Sweden November 21, 1938 2 Claims.

The present invention relates to a tool holder which permits a readilyeffected and reliable clamping of a tool on a shaft end and likewise arapid release of the tool. The essential feature of the invention isthat the holder comprises a socket or sleeve adapted to be pushed on theshaft end, said socket or sleeve carrying a set of balls adapted toengage recesses formed in the shaft and to remain in this engagement bythe action of a ring slidably mounted on the socket or sleeve which isformed with a conical or similar inner surface which in the displacementof the ring in one direction forces the balls into said recesses and inthe displacement of the ring in the other direction releases the ballsfrom said engagement.

In the accompanying drawing two embodiments of the invention are shown.Fig. 1 is a side elevation, partly in section, of a tool holderaccording to one embodiment as used for clamping a grinding disc to ashaft end of a grinding machine. Fig. 2 is a side elevation, partly insection, of a tool holder according to the other embodiment.

It is to be noted that while the invention is illustrated as embodied ina grinding disc holder, it may also be used for many other purposes,without departing from its principle.

With reference to Fig. 1, the numeral I indicates a shaft end of thegrinding machine. Pushed on the, preferably conical, shaft end is asocket 2 forming part of a holder for a grinding disc 3 clamped againsta wheel-shaped portion 4 of the socket by means of a screw 5 engaging athreaded central bore in the bottom of the socket. The means shown inthe drawing for clamping the tool to the holder do not form anyessential parts of this invention, but may be varied according to thekind of the tool.

The socket 2 is formed with a circular set of holes extending throughthe side wall of the socket and each adapted to receive a ball 6 thediameter of which is larger than the radial thickness of the side wallof the socket. The balls may move in and out in their holes. The socketis surrounded by a slidable ring I having a conical inner surface 8adapted to engage the balls in order to force them inwardly or allowthem to roll outwardly, according to whether the ring is moved in onedirection or the other. Inserted between the ring 7 and the wheelshapedportion 4- 0f the socket is a helical spring 9, which tends to displacethe ring outwardly. Preferably, the holes in the side wall of the socketmay be contracted slightly at their inner ends to permit the balls toproject only to a predetermined extent into the bore of the socket. Bythis feature the balls are caused to act as stops to check the tendencyof the spring to displace the ring outwardly.

The bore of the socket 2 is adapted to fit snugly on the conical surfaceof the shaft end I. When the socket is placed on the shaft end andpushed inwardly thereon as far as possible, the balls 6 engagecorresponding recesses formed in the conical surface of the shaft endand are retained in said engagement by the action of the spring loadedring I. This position is shown in Fig. 1. While the shaft is inrotation, the ball will, consequently, act as catch members causing thesocket 2 and thus also the grinding disc to rotate with the shaft end.

The mounting of the tool holder may be readily effected. To this end theoperator with his one hand pushes the ring 1 towards the wheelshapedportion 4 against the action of the spring 9, while with his other handhe places the socket 2 on the shaft end and pushes it thereon as far aspossible. Then, the operator need only turn the holder until the balls 6come in register with the recesses of the shaft end I and release thering I, in order to lock the holder to the shaft end, the released ringbeing displaced outwardly by the spring, until it forces the balls intoen-' gagement with the recesses. The ring then automatically maintainsthe balls in this engagement.

The embodiment shOWn in Fig. 2 differs from that above described in thatthe ring I is provided with an inwardly extending projection ID of anequal inner but smaller outer diameter than that of the ring 1. Theshoulder thus formed between the ring I and its projection l0 affords anupper support for the spring 9 guided by the projection H3, The latteris such an axial length as to abut against the wheelshaped portion 4, asthe conical surface 8 of the ring releases the balls 6, the projectionl0 at the same time limiting the compression of the spring 9.

A screw I! provided at the upper edge of the socket 2 forms a stop forlimiting the outward displacement of the ring 1. This embodiment iscompletely self-contained, in as much as its various parts can bedismantled only after a removal of the screw II.

In both of the figures of the drawing the ring I is serrated tofacilitate its operation. In Fig. 2 one of the recesses in the shaft isshown at I2, as seen in front view.

What I claim is:

1. A tool holder comprising in combination, a tapered shaft end having aring of separate concave recesses in its tapered surface, a socketcomprising a side wall having a conical inner surface to accommodatesaid tapered end and a disc-shaped bottom member to engage the tool,said side wall having a ring of through-extending holes, a ball in eachof said holes, a ring slidably mounted on said side wall, said ringhaving a conical inner surface adapted upon a displacement of the ringin one direction to force the balls inwards, in order to cause them toengage the concave recesses in the tapered surface of the shaft end, ahelical spring to effect said displacement of the ring, and a reducedextension of said ring for guiding and limiting the compression thereofand also limiting the retraction of the ring to release the balls.

2. A tool holder comprising in combination, a 20 tapered shaft end,having a ring of separate concave recesses in its tapered surface, asocket comprising a side wall having a conical inner surface toaccommodate said tapered shaft end and a disc-shaped bottom member toengage the tool, said side wall having a ring of throughextending holes,a ball in each of said holes, a ring rotatably and slidably mounted onsaid side wall, said ring having a conical inner surface adapted upon adisplacement of the ring in one direction to force the ball inwards, inorder to cause them to engage the recesses in the tapered surface of theshaft end, a helical spring to effect said displacement of the ring,means on the side wall of said socket to limit said displacement, and areduced extension of said ring for guiding said spring and limiting thecompression thereof and also limiting the retraction of the ring torelease the balls.

SIGFRID LINUS STENBERG.

